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SC MVA (1,2,0)

SC MVA (1,2,0)

SC MVA (1,2,0)

(OP)
Can someone explain me for a system, How to get a SC MVA (1, 2 and 0) and respective X/R. I want this to calculate various fault currents.

System is 3.15MVA 33/11kV Transformer, 11kV Secondary of this T/F connected to Transmission lines connected to various other 11kV/400V Transformers and then to loads.

Generally upto now I have calculated SCMVA of T/F from TF-MVAx100/%Z and source MVA I got from standards or Utilities. I am confused by SC MVA (1,2,0)

Kindly help

RE: SC MVA (1,2,0)

Does "SC MVA" refer to short circuit calculations with the so called MVA-method? If so, then it might be an idea to get used to the normal methods (text-book, standard). They may be more useful in the long run. Several commercial and free programs are available.

RE: SC MVA (1,2,0)

1,2,0 refers to positive, negative and zero sequences?

To figure out the transformer impedance you short the secondary with and ammeter and apply a low voltage in primary side and increase voltage until the secondary currents is the rated secondary current of the xfmr.  note the secondary is shorted and measure the primary voltage.  divide the voltage obtained by the primary voltage of the xfmr and multiply by a 100 for %z.  the %z is the actual or leakage impedance refered to the low voltage side.  

%z=IZ/v and
z=%z*v/I refered to lv side.

%r = full load low voltage losses / xfmr rating in va.  according to the ieee red book you use the self cooling va value without fans and oil.  

r=full load losses / I*I refered to lv side.

%x=sqrt (%z^2-%r^2)
Pu Imp = % imp/100 or actual imp/ base imp
where the base imp = v/I (rated values of base side)
kv*kv*1000/kva

here is a starting point.
 

RE: SC MVA (1,2,0)

Just to help you with your homework remember all passive plant, the positive and negative sequence impedances (Z1 and  Z2) of a transformer are identical.

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